TELECOM Digest OnLine - Sorted: Re: Device That Interfaces Between Phone/CallerID and Serial Port?

Re: Device That Interfaces Between Phone/CallerID and Serial Port?

Gordon Burditt (
Wed, 12 Oct 2005 18:36:21 -0000

>> Assuming you are looking for a device that receives Caller-ID, and the
>> voice menu stuff is done by something else, ..

> That's a very bad assumption. It's the voice-menu touch-tone: press 1
> if you are a personal acquaintance whose first name I would recognize;
> press 2 if you are calling me in regard to an existing business
> relationship such as a credit card or bank account; press 3 if you are
> a stranger trying to call me to advertise a product or service; press
> 4 if you are offering me a job; press 5 if you are a stranger trying
> to call for personal reasons such as you want to discuss something
> interesting I posted in a newsgroup; press 6 if we met in person but I
> don't yet know your name but I'd remember meeting you.) which I don't
> have and am seeking.

Since you didn't ask for a way for this device to transfer calls to
other phones, I don't see how it's going to work even if it does the
voice menus and the touch-tone decoding.

> Do you know what such a device would be called and which newsgroup
> would be appropriate for asking about such devices? It would be nice
> if that one device also included decoding of caller-ID, so that I can
> put up different touch-tone monus depending on whether the call
> provides caller-ID or not and if so then whether the call is from
> somebody whose number I already know, and if a number I already know
> then depending on the number: -- You have harassed me and I asked you
> to stop calling. But here you go calling me to harass me again. Your
> call will be reported to the police. -- Hi daddy. Phone is ringing
> now. If I'm here, I'll answer shortly. -- Hi Margaret. Nice to hear
> from you. If I'm here, I'll answer shortly.

>> "a cheap modem". It needs Caller-ID but it doesn't need 56K or even
>> 33.6k speeds. You don't want to set it up to auto-answer. The modem's
>> RING response code will include caller-ID if it's set up to return it.

> I already have a modem, a SupraExpress 56. When the phone rings, the
> modem sends just the word RING on a line by itself, with a blank line
> between consecutive RINGs. I don't know of any way to make it detect
> caller-ID and report that.

Reasonably modern modems (anything over, say, 7 years old) should be
settable to report caller-ID, typically with a command of the form
ATX<something goes here> , although what the something is varies with
the modem. Of course, you need caller-ID on the line.

>> The various Digium PCI cards used by Asterisk to interface with analog
>> phone lines let you do a lot more, including the voice menu stuff
>> itself, but they don't do RS-232.

> I don't think a mere "card" would be of any use to me. It doesn't
> sound like anything I can connect up to a phone line and
> program/configure in any simple manner.

The card is a hardware interface to a telephone line (or several
lines. One exists to handle a whole T1, for example. Another handles
up to 4 analog phones and/or phone lines on one card). The software
is Asterisk, which gives you all sorts of abilities like a small
business PBX, voice menus, voice mail with hundreds or thousands of
mailboxes, VOIP gateway, etc. I'm not sure whether there is any other
software that uses these cards.

> But just in case I'm mistaken
> in rejecting your suggestion, please tell me how somebody would
> program the "card" to set up the various touch-tone menus? Is there a
> keypad on the "card" for entering configuration commands, and a LED or
> LCD display on the "card" for getting responses to verify what I'm
> doing?

Asterisk configuration files aren't that friendly but they allow a lot
of flexibility. I think there are some more friendly front-ends for
the configuraton. You can do lots of menus, playing a recording and
then branching on what tones were entered - as many levels as you
want. (The distribution comes with an interesting "telemarketer
torture" set of voice menus that illustrate all the BAD things to do
with voice menus: loops, commonly used options LAST, etc.)

You can also do things like sending the call to voice mail, forward it
to an extension (possibly trying several in sequence), hanging up,
etc. The number of different voice prompts you can record is limited
essentially by the size of your hard disk. You can route based on
caller-ID. You can do caller-ID blacklists (and unlike the ones sold
by the phone company, having a blacklist a couple hundred thousand
numbers long is possible and shouldn't slow things down much).

For an Asterisk setup, you'd probably want a dedicated PC on 24x7.
You don't have to dedicate it, but for reliability it's probably

> * See any DTMF digits dialed ON INBOUND CALLS! Use this to verify
> what mailbox was dialed along with the Caller ID number! I assume
> DTMF is the technical name/abbreviation for the tones used by "touch
> tone" dialing. In the absense of any outgoing message, there's no
> reason anyone would key in any DTMF tones after getting a connection,
> so by itself this is of no use here.

Some gadgets have a pre-canned "please enter your passcode now" prompt
which you can't change. This is of limited usefulness, especially for
your purposes.

> I really need something that will enforce a touch-tone (DTMF) menu,
> which anonymous or other unknown/suspicious callers must traverse
> before they will be allowed to ring my phone. I don't see any
> indication that Whozz will provide that capability. If there's no such
> device that handles both touch-tone menus and caller-ID decoding to
> pick which menu to use at the start, then I'd settle for a device that
> didn't have any caller-ID decoding at all, merely uses the same
> touch-tone menu for all callers, and rings my phone only if the caller
> passes a "Turing" test for establishing the person as a known friendly
> acquaintance or relative. (I currently get ten to twenty harassing
> calls per day, and maybe one or two non-harassing calls per month. I
> would like the touch-tone menu to filter out everything except those
> very few non-harassing calls.)

You haven't indicated much about what you want the caller to be able
to talk to *BESIDES* voice menus. What does it do with the call after
that? Forward it to a phone with a live person? (how is that phone
connected)? How many possible different live people on how many
different phones? Forward it into voice mail? (what provides that
and how do you reach it)?

Gordon L. Burditt

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